/* ----------------------------------------------------------------------
* Copyright (C) 2010 ARM Limited. All rights reserved.
*
* $Date:        15. February 2012
* $Revision: 	V1.1.0
*
* Project: 	    CMSIS DSP Library
* Title:		arm_cmplx_dot_prod_q31.c
*
* Description:	Q31 complex dot product
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Version 1.1.0 2012/02/15
*    Updated with more optimizations, bug fixes and minor API changes.
*
* Version 1.0.10 2011/7/15
*    Big Endian support added and Merged M0 and M3/M4 Source code.
*
* Version 1.0.3 2010/11/29
*    Re-organized the CMSIS folders and updated documentation.
*
* Version 1.0.2 2010/11/11
*    Documentation updated.
*
* Version 1.0.1 2010/10/05
*    Production release and review comments incorporated.
*
* Version 1.0.0 2010/09/20
*    Production release and review comments incorporated.
* -------------------------------------------------------------------- */

#include "arm_math.h"

/**
 * @ingroup groupCmplxMath
 */

/**
 * @addtogroup cmplx_dot_prod
 * @{
 */

/**
 * @brief  Q31 complex dot product
 * @param  *pSrcA points to the first input vector
 * @param  *pSrcB points to the second input vector
 * @param  numSamples number of complex samples in each vector
 * @param  *realResult real part of the result returned here
 * @param  *imagResult imaginary part of the result returned here
 * @return none.
 *
 * <b>Scaling and Overflow Behavior:</b>
 * \par
 * The function is implemented using an internal 64-bit accumulator.
 * The intermediate 1.31 by 1.31 multiplications are performed with 64-bit precision and then shifted to 16.48 format.
 * The internal real and imaginary accumulators are in 16.48 format and provide 15 guard bits.
 * Additions are nonsaturating and no overflow will occur as long as <code>numSamples</code> is less than 32768.
 * The return results <code>realResult</code> and <code>imagResult</code> are in 16.48 format.
 * Input down scaling is not required.
 */

void arm_cmplx_dot_prod_q31(
    q31_t* pSrcA,
    q31_t* pSrcB,
    uint32_t numSamples,
    q63_t* realResult,
    q63_t* imagResult)
{
	q63_t real_sum = 0, imag_sum = 0;              /* Temporary result storage */

#ifndef ARM_MATH_CM0

	/* Run the below code for Cortex-M4 and Cortex-M3 */
	uint32_t blkCnt;                               /* loop counter */


	/*loop Unrolling */
	blkCnt = numSamples >> 2u;

	/* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
	 ** a second loop below computes the remaining 1 to 3 samples. */
	while(blkCnt > 0u) {
		/* CReal = A[0]* B[0] + A[2]* B[2] + A[4]* B[4] + .....+ A[numSamples-2]* B[numSamples-2] */
		/* Convert real data in 2.62 to 16.48 by 14 right shifts */
		real_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14;
		/* CImag = A[1]* B[1] + A[3]* B[3] + A[5]* B[5] + .....+ A[numSamples-1]* B[numSamples-1] */
		/* Convert imag data in 2.62 to 16.48 by 14 right shifts */
		imag_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14;

		real_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14;
		imag_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14;

		real_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14;
		imag_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14;

		real_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14;
		imag_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14;


		/* Decrement the loop counter */
		blkCnt--;
	}

	/* If the numSamples  is not a multiple of 4, compute any remaining output samples here.
	 ** No loop unrolling is used. */
	blkCnt = numSamples % 0x4u;

	while(blkCnt > 0u) {
		/* CReal = A[0]* B[0] + A[2]* B[2] + A[4]* B[4] + .....+ A[numSamples-2]* B[numSamples-2] */
		real_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14;
		/* CImag = A[1]* B[1] + A[3]* B[3] + A[5]* B[5] + .....+ A[numSamples-1]* B[numSamples-1] */
		imag_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14;

		/* Decrement the loop counter */
		blkCnt--;
	}

#else

	/* Run the below code for Cortex-M0 */

	while(numSamples > 0u) {
		/* outReal = realA[0]* realB[0] + realA[2]* realB[2] + realA[4]* realB[4] + .....+ realA[numSamples-2]* realB[numSamples-2] */
		real_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14;
		/* outImag = imagA[1]* imagB[1] + imagA[3]* imagB[3] + imagA[5]* imagB[5] + .....+ imagA[numSamples-1]* imagB[numSamples-1] */
		imag_sum += (q63_t) * pSrcA++ * (*pSrcB++) >> 14;

		/* Decrement the loop counter */
		numSamples--;
	}

#endif /* #ifndef ARM_MATH_CM0 */

	/* Store the real and imaginary results in 16.48 format  */
	*realResult = real_sum;
	*imagResult = imag_sum;
}

/**
 * @} end of cmplx_dot_prod group
 */
